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How the Environment Shapes Societies

Learn how water, landforms, climate and resources shape where and how people live, how they change the environment, and how to read thematic maps and data.

Practice this skill 20 min Environment and societal development Leer en español
Key idea

What you'll learn

In plain words: the land shapes where and how people live, and people change the land in return.

Why do so many people live along rivers and coasts? Why do so few live in deserts and mountains? Why did farming begin in some places first? And what happens when people change the land too much? This lesson covers how the physical environment — the natural land, water, and climate — shapes human societies. It also covers how people shape the environment in return.

You will learn to:

  • explain settlement patterns using water, landforms, climate, and resources;
  • describe how agriculture developed and how it changed human life;
  • classify human–environment interaction as depend, adapt, or modify;
  • weigh renewable and nonrenewable resources and sustainability;
  • read thematic maps, legends, grid coordinates, and map scales;
  • calculate percent change and population density.

How it shows up on the GED: expect maps of real or made-up places. You may also see charts of rainfall, population, or resource use, or short passages about events like the Dust Bowl. Questions ask you to:

  • read a legend or measure a distance;
  • explain why a city grew where it did;
  • connect a cause to its effect.
Words to know

Key terms

  • physical geography — natural features: landforms, water, climate, soil, plants (the Rocky Mountains, the Mississippi River).
  • human geography — how people live, settle, and use the land (cities, farms, highways).
  • settlement pattern — where people choose to live and how close together (towns strung along a river).
  • climate — the usual weather of a place over many years (a desert gets under 10 inches of rain a year).
  • natural resource — something from nature that people use (water, timber, coal, fertile soil).
  • renewable resource — one that nature replaces fairly quickly (sunlight, wind, forests if replanted).
  • nonrenewable resource — one that cannot be replaced in a human lifetime (oil, coal, natural gas, copper).
  • irrigation — bringing water to crops through canals, pipes, or ditches.
  • oasis — a fertile spot in a desert with a water source such as a spring.
  • erosion — wearing away of soil or rock by wind or water.
  • human–environment interaction — the ways people depend on, adapt to, and modify their surroundings.
  • sustainability — using resources in ways that meet today's needs without ruining them for the future.
  • conservation — careful use and protection of natural resources (national forests, soil-saving farming).
  • thematic map — a map that shows one topic, such as rainfall, population, or resources.
  • legend (key) — the box that explains a map's symbols and colors.
  • map scale — shows how distance on the map relates to real distance (1 inch = 100 miles).
  • population density — people per unit of area (240 people per square mile).

All Social Studies words in the glossary

Why people settle where they do

In plain words: people live where they can get water, food, shelter, safety, and trade.

Think about choosing a new apartment. You want water and power, stores nearby, and a safe street. Whole towns grew the same way. People settle where they can meet basic needs: water, food, shelter, and safety. They also want ways to trade. Four physical factors matter most:

  1. Water. People need fresh water for drinking, farming, and industry. Rivers also serve as highways. That's why great cities grew on rivers and coasts: Cairo on the Nile, St. Louis on the Mississippi, New York at the mouth of the Hudson.
  2. Landforms. Flat plains and river valleys are easy to farm and build on. Steep mountains are hard to farm and travel through. So mountains have fewer people. Mountain towns often exist for one resource, such as mining.
  3. Climate. Moderate temperatures and enough rain support farming. Very dry (desert) or very cold (polar) climates support few people. The exception is where water is available, as at an oasis or along a river like the Nile.
  4. Resources. Coal, iron, gold, timber, fish, and fertile soil attract settlers. The California Gold Rush of 1849 created towns almost overnight.

Example: On a map, a large city sits where a river meets the ocean. The best explanation is access to trade by both sea and river. Nearby farmland helps too.

Schematic map of an imaginary land, not a real place, showing why people settle where they do. A compass rose shows north at the top. An ocean lies on the west. A river flows west from mountains in the north-east across flat plains to the ocean. The largest city sits where the river meets the ocean (trade by sea and river). Medium towns sit along the river on the flat farmland. A small mining town sits in the mountains. A desert covers the south, nearly empty except for a small town at an oasis with a spring. A legend shows large, medium and small dots for city size. Why people settle where they do (schematic, imaginary land) OCEAN Mountains River Flat plains: good farmland Desert (very dry) Largest city: river meets the ocean River town River town Mining town Oasis town (spring) N S E W Legend large city town small town river

Human factors matter too. Railroads, highways, and jobs can make a place grow. This can happen even if its natural setting is ordinary.

Agriculture changes everything

In plain words: when people learned to farm, they could stay in one place, and villages grew into cities.

For most of human history, people were hunter-gatherers. They moved from place to place to follow food. About 10,000 years ago, people in the Fertile Crescent of Southwest Asia began to domesticate — tame and raise — plants (wheat, barley) and animals (sheep, goats). Farming also began on its own in other places:

  • rice in China;
  • corn (maize) in Mexico;
  • potatoes in the Andes.

This change is called the Agricultural (Neolithic) Revolution.

Effects of farming:

  • Food surpluses → larger populations and permanent villages.
  • Surpluses freed some people to become specialists: potters, priests, soldiers, traders.
  • Villages grew into cities. Governments and writing developed to manage land, water, and taxes.
  • New problems appeared. Crowded settlements spread disease, and people fought over land and water.

The environment set the rules. Early farmers chose river valleys with fertile silt and reliable water. Where rain was scarce, they modified the land with irrigation canals (Mesopotamia, Egypt). Where land was steep, they carved terraces — flat steps — into hillsides (the Inca in the Andes; rice growers in Asia). The crops a region could grow shaped its diet, trade, and wealth.

Example: A question asks why the earliest civilizations formed in river valleys. Best answer: rivers provided water for irrigation and fertile soil. That allowed food surpluses.

Human–environment interaction and sustainability

In plain words: people use nature, adjust to it, or change it — and changing it can backfire.

Think about a rainy climate. You can collect rainwater (use it), buy a raincoat (adjust to it), or dig a ditch to drain your yard (change it). Geographers describe the same three kinds of interaction:

TypeMeaningExamples
DependUse what nature providesFishing, drinking from a lake, using wood for fuel
AdaptChange behavior or buildings to fit natureWarm clothing, homes on stilts in flood zones, thick walls in deserts
ModifyChange the land, water, or plantsDams, irrigation canals, clearing forests, filling wetlands
Three panels comparing kinds of human-environment interaction. Depend: a person fishing from a lake, using what nature provides. Adapt: a house on stilts above flood water, changing buildings or behavior to fit nature. Modify: a dam across a river with a reservoir behind it, changing the land or water. Below each panel are more examples: depend, drinking lake water and burning wood; adapt, warm clothing and thick desert walls; modify, irrigation canals and clearing forests. Depend use what nature provides fishing, drinking lake water, wood for fuel Adapt fit your life to nature warm clothing, homes on stilts, thick desert walls Modify change the land or water dams, irrigation canals, clearing forests lake flood water reservoir dam river

Modifying the environment brings benefits. But it can also have unintended consequences — results nobody planned:

  • The Dust Bowl (1930s): farmers plowed the grasslands of the southern Great Plains. Then drought came. Wind blew away the bare topsoil, and many families lost their farms. In 1935 Congress created the Soil Conservation Service. It taught soil-saving methods such as contour plowing, crop rotation, and windbreaks.
  • The Aral Sea (Central Asia): beginning in the 1960s, Soviet planners diverted the two rivers that fed this huge lake. They used the water to irrigate cotton. The lake shrank dramatically. Fishing towns were left far from the water, and salty dust blew across farmland.
Human-environment cause and response chain for the Dust Bowl of the 1930s. Farmers plow up the grasslands of the southern Great Plains (people modify the land). Drought comes. Wind blows the bare topsoil away in dust storms. Many families lose their farms and leave. In 1935 Congress creates the Soil Conservation Service. It teaches contour plowing, crop rotation and windbreaks, which protect the soil on the farms, closing the loop. The Dust Bowl: modify, consequence, response People modify Farmers plow up Plains grassland Drought 1930s: little rain Topsoil blows away bare soil, no grass roots to hold it Farms lost many families leave the Plains Response: Soil Conservation Service (1935) teaches contour plowing, crop rotation, and windbreaks Soil protected farming can continue with soil-saving methods back to farming, more carefully

Sustainability asks a simple question: can we keep using a resource without using it up? It is like a paycheck. If you spend only what comes in, the money lasts.

  • Renewable resources (sun, wind, water power, replanted forests) can last if managed well.
  • Nonrenewable resources (coal, oil, gas, metals) will run out.

In the early 1900s, President Theodore Roosevelt led the conservation movement. It protected millions of acres as national forests, parks, and wildlife refuges. Yellowstone had already become the first national park in 1872.

Map skills: legends, grids, scale, and thematic maps

Map of Teravia, a fictional country, on a grid with columns A–F and rows 1–5; each grid square is 100 miles wide (scale bar: 90 pixels = 100 miles). The Western Ocean lies along the west edge (column A). Forest (over 40 inches of rain a year) covers row 1 and the top of row 2 in columns A–D. Grassland plains (20–40 inches of rain) cover the middle of the country. Desert (under 10 inches of rain) covers row 5. Mountains cover columns E and F in rows 1–4. The Amon River begins in the mountains in square F1/F2 and flows west through row 3 to the ocean. Cities: Port Sela (over 1,000,000 people) at the mouth of the river on the coast, square A3; Darro (250,000–1,000,000) on the river in square C3, exactly 200 miles east of Port Sela; Kesh (under 250,000) in the desert in square C5 next to a spring (underground water); Halven (under 250,000) in the mountains in square E4 next to a copper mine; Brinmoor (under 250,000) in the forest in square C1. Western Ocean Amon River A B C D E F 1 2 3 4 5 Port Sela Darro Kesh Halven Brinmoor N Legend Forest (over 40 in. of rain a year) Grassland plains (20–40 in. of rain) Desert (under 10 in. of rain) Mountains City over 1,000,000 people City of 250,000–1,000,000 Town under 250,000 Spring (underground water) Copper mine River 0 100 200 miles (each grid square is 100 miles wide) Teravia (a fictional country)

In plain words: read the title and the legend first; they tell you what the map is about and what its symbols mean.

Start every map with the title and the legend. The title tells you the topic and the place. The legend tells you what each symbol, color, or pattern means.

Kinds of maps you'll see:

  • Political maps: borders, countries, states, cities.
  • Physical maps: mountains, rivers, elevation.
  • Thematic maps: one topic, such as rainfall, population density, land use, resources, or migration. Darker shading usually means "more."

Locating places:

  • A letter-number grid names squares, like seats in a stadium (Kesh is in C5: column C, row 5).
  • Latitude lines run east–west. They measure distance north or south of the equator (0°).
  • Longitude lines run north–south. They measure distance east or west of the prime meridian (0°).
  • Write latitude first: 32°N, 44°E.
  • A compass rose or north arrow shows direction.
A sample schematic map labeled with its five parts. 1, Title: Sample Land, Land Use, at the top. 2, Legend: a box explaining symbols for city, river and forest. 3, Letter-number grid: columns A to D and rows 1 to 3; the city is in square B2. 4, Compass rose: N, E, S, W, with north at the top. 5, Scale bar: 0, 100 and 200 miles, where one grid square is 100 miles wide. Sample Land: Land Use A B C D 1 2 3 Lakeview N S E W 0 100 200 miles Legend city river forest 1 2 3 4 5 1 Title: topic and place 2 Legend: what symbols mean 3 Grid: Lakeview is in B2 4 Compass rose: direction 5 Scale bar: 1 square = 100 mi

Measuring distance with a scale:

  1. Measure the map distance. Use the scale bar, grid squares, or the edge of your erasable note board.
  2. Compare it with the scale. Say one grid square = 100 miles. Two places 2 squares apart are 200 miles apart.

Example: On the map of Teravia, Brinmoor (C1) and Kesh (C5) are almost straight north–south of each other. They are about 4 grid squares apart. So they are roughly 400 miles apart.

Close-up of grid columns B, C and D, rows 1 to 5, of the Teravia map. Brinmoor is in square C1 and Kesh is in square C5, straight north-south of each other. A double arrow between them crosses 4 grid squares, numbered 1 to 4. Each square is 100 miles, so the distance is 4 times 100 equals 400 miles. A scale bar shows 0 to 100 miles equal to one square. B C D 1 2 3 4 5 Brinmoor (C1) Kesh (C5) 1 2 3 4 Count the squares: C1 to C5 = 4 squares Use the scale: 1 square = 100 miles Multiply: 4 × 100 = 400 miles 0 100 miles scale bar
Formula

Two calculations you may need

Percent change (used for shrinking lakes, growing populations, rising resource use):

\text{percent change} = \dfrac{\text{new value} - \text{original value}}{\text{original value}} \times 100

A negative result is a decrease. Always divide by the original (earlier) value.

Example: a forest covers 80,000 acres in 1990 and 60,000 acres in 2020. Change = 60{,}000 - 80{,}000 = -20{,}000. Then \dfrac{-20{,}000}{80{,}000} \times 100 = -25, a 25% decrease.

Population density:

\text{population density} = \dfrac{\text{population}}{\text{land area}}

Example: 1,200,000 people living on 5,000 square miles: \dfrac{1{,}200{,}000}{5{,}000} = 240 people per square mile.

The Social Studies test has no formula sheet, so learn them. The on-screen calculator is available for questions that need it.

Worked example

Example 1: Explaining a settlement with a map

Map of Teravia, a fictional country, on a grid with columns A–F and rows 1–5; each grid square is 100 miles wide (scale bar: 90 pixels = 100 miles). The Western Ocean lies along the west edge (column A). Forest (over 40 inches of rain a year) covers row 1 and the top of row 2 in columns A–D. Grassland plains (20–40 inches of rain) cover the middle of the country. Desert (under 10 inches of rain) covers row 5. Mountains cover columns E and F in rows 1–4. The Amon River begins in the mountains in square F1/F2 and flows west through row 3 to the ocean. Cities: Port Sela (over 1,000,000 people) at the mouth of the river on the coast, square A3; Darro (250,000–1,000,000) on the river in square C3, exactly 200 miles east of Port Sela; Kesh (under 250,000) in the desert in square C5 next to a spring (underground water); Halven (under 250,000) in the mountains in square E4 next to a copper mine; Brinmoor (under 250,000) in the forest in square C1. Western Ocean Amon River A B C D E F 1 2 3 4 5 Port Sela Darro Kesh Halven Brinmoor N Legend Forest (over 40 in. of rain a year) Grassland plains (20–40 in. of rain) Desert (under 10 in. of rain) Mountains City over 1,000,000 people City of 250,000–1,000,000 Town under 250,000 Spring (underground water) Copper mine River 0 100 200 miles (each grid square is 100 miles wide) Teravia (a fictional country)

Use the map of Teravia.

Question: Why is Brinmoor most likely a small town rather than a large city? A. It lies in a desert. B. It lies in a forest, away from the river and the coast. C. It sits at the mouth of a river. D. It is in the mountains.

Think aloud:

  1. "I find Brinmoor in square C1. The pattern around it matches forest in the legend."
  2. "It is not on the Amon River and not on the coast, so it lacks easy water transportation."
  3. "A is wrong because the desert is row 5. C describes Port Sela. D describes Halven."

Answer: B. Small towns often depend on one local resource (here, probably lumber). They lack the transportation advantages that make big cities grow.

Worked example

Example 2: Reading two charts together

Two bar charts for five regions of the fictional country Teravia. Average rainfall in inches per year and population density in people per square mile: Northern Forest: 48 inches, 15 people per sq. mile; Central Plains: 30 inches, 60 people per sq. mile; Amon River Valley: 28 inches, 240 people per sq. mile; Eastern Mountains: 35 inches, 8 people per sq. mile; Southern Desert: 7 inches, 4 people per sq. mile. Average rainfall (inches per year) Population density (people per sq. mile) 0 10 20 30 40 50 0 50 100 150 200 250 Northern Forest 48 15 Central Plains 30 60 Amon River Valley 28 240 Eastern Mountains 35 8 Southern Desert 7 4 Rainfall and Population Density in Five Regions of Teravia (fictional data)

The rainfall and density chart shows: Northern Forest 48 in. of rain, 15 people per sq. mi; Amon River Valley 28 in., 240 people per sq. mi.

Question: Which statement does the data support?

Think aloud:

  1. "The forest has much more rain but far fewer people. So rain doesn't predict population here."
  2. "The valley has a river (from the map). That explains its high density."
  3. "I'll reject any choice that says more rain always means more people. One counterexample disproves always."

Answer: Factors other than rainfall, such as access to a river, strongly affect population density.

Worked example

Example 3: Percent change from a table

Lake Corvan's area: 1960 = 26,000 sq. mi; 1980 = 19,500 sq. mi.

Question: By what percent did the lake shrink from 1960 to 1980?

Think aloud:

  1. "Change = 19{,}500 - 26{,}000 = -6{,}500."
  2. "Divide by the original, 26,000: \dfrac{6{,}500}{26{,}000} = 0.25."
  3. "Times 100 = 25. It shrank 25%."
  4. "Trap check: if I divided by 19,500 I'd get about 33%, which uses the wrong base."
Bar model of Lake Corvan, a fictional lake. The 1960 bar shows 26,000 square miles, divided into four equal parts of 6,500. The 1980 bar shows 19,500 square miles, three of the four parts. The missing part, 6,500 square miles, is one quarter of the original 26,000, so the lake shrank by 25 percent. Divide by the original 1960 value. Lake Corvan (fictional): area in square miles 1960 6,500 6,500 6,500 6,500 26,000 1980 19,500 lost 6,500 original = 26,000 (divide by this) 6,500 ÷ 26,000 = 0.25 = 25% decrease (1 of 4 equal parts)

Answer: a 25% decrease.

Worked example

Example 4: Cause and effect in a passage

Read: "In the 1960s, planners diverted the two rivers that fed the Aral Sea to irrigate cotton fields. Over the next decades the sea shrank so much that fishing boats were left stranded on dry land, and winds carried salty dust onto nearby farms."

Question: Which statement best describes the relationship in the passage? A. Salty dust caused the rivers to be diverted. B. Diverting river water for irrigation caused the sea to shrink, which harmed fishing and farming. C. Fishing caused the sea to shrink. D. Cotton farming had no effect on the Aral Sea.

Think aloud:

  1. "The first event is the diversion of the rivers. That's the cause."
  2. "Effects follow: the sea shrinks → boats stranded → salty dust on farms."
  3. "A reverses the order. C picks the wrong cause. D contradicts the passage."
Cause and effect chain for the Aral Sea. Cause, 1960s: planners divert the two rivers that fed the sea to irrigate cotton. Effect: the sea shrinks over the next decades. Further effects: fishing boats are stranded on dry land, and winds carry salty dust onto nearby farms. Cause → effect → further effects CAUSE (1960s) Two rivers that fed the Aral Sea diverted to irrigate cotton EFFECT The sea shrinks over decades FURTHER EFFECT Fishing boats stranded on dry land FURTHER EFFECT Winds carry salty dust onto nearby farms A trap answer reverses the order. Find the first event: that is the cause.

Answer: B. Map the chain: cause → effect → further effect.

Common mistake

Common mistakes

  • Skipping the legend. Wrong: guessing what a dotted pattern means. Right: check the legend first; on the Teravia map, small black dots mean desert and green dots mean forest.
  • Treating one factor as the whole story. Wrong: "More rain always means more people." Right: rivers, landforms, and resources also matter; look for exceptions.
  • Mixing up adapt and modify. Wrong: "Building a dam is adapting." Right: a dam changes the river, so it modifies the environment. Wearing warm clothes is adapting.
  • Dividing by the wrong number in percent change. Wrong: change ÷ new value. Right: change ÷ original value.
  • Confusing causes with responses. Wrong: "The Soil Conservation Service caused the Dust Bowl." Right: it was created after the storms to fix the problem.
  • Misreading the scale. Wrong: assuming a square is 1 mile. Right: read the scale bar (on the Teravia map, each square is 100 miles).
Test strategy

GED strategy

  • Title → legend → scale → question. Spend 15 seconds orienting yourself on any map before reading the choices.
  • Point to the evidence. For each answer, ask: "Where on the map, chart, or passage does it say this?" If you can't point to it, eliminate it.
  • Check axes and units on charts (inches vs. people per square mile). Two charts side by side may use different scales.
  • Hunt for exceptions. When a pattern seems obvious, look for a region that breaks it. The GED often asks you to explain the exception.
  • Watch absolute words (always, never, no one, all). Data rarely support them.
  • Use the calculator for percent change and density. Write the formula on your note board first, then plug in the numbers.

Check yourself

Environment and societal development
A Map of Teravia

The map below shows land types, cities, and resources in Teravia, a fictional country. Use the legend and the scale bar to answer the questions.

Map of Teravia, a fictional country, on a grid with columns A–F and rows 1–5; each grid square is 100 miles wide (scale bar: 90 pixels = 100 miles). The Western Ocean lies along the west edge (column A). Forest (over 40 inches of rain a year) covers row 1 and the top of row 2 in columns A–D. Grassland plains (20–40 inches of rain) cover the middle of the country. Desert (under 10 inches of rain) covers row 5. Mountains cover columns E and F in rows 1–4. The Amon River begins in the mountains in square F1/F2 and flows west through row 3 to the ocean. Cities: Port Sela (over 1,000,000 people) at the mouth of the river on the coast, square A3; Darro (250,000–1,000,000) on the river in square C3, exactly 200 miles east of Port Sela; Kesh (under 250,000) in the desert in square C5 next to a spring (underground water); Halven (under 250,000) in the mountains in square E4 next to a copper mine; Brinmoor (under 250,000) in the forest in square C1. Western Ocean Amon River A B C D E F 1 2 3 4 5 Port Sela Darro Kesh Halven Brinmoor N Legend Forest (over 40 in. of rain a year) Grassland plains (20–40 in. of rain) Desert (under 10 in. of rain) Mountains City over 1,000,000 people City of 250,000–1,000,000 Town under 250,000 Spring (underground water) Copper mine River 0 100 200 miles (each grid square is 100 miles wide) Teravia (a fictional country)

Based on the map, which factor best explains why Port Sela is the largest city in Teravia?

Answer choices
Hint

Look at where Port Sela sits. Which two kinds of water meet there?

Check yourself

Environment and societal development
A Map of Teravia

The map below shows land types, cities, and resources in Teravia, a fictional country. Use the legend and the scale bar to answer the questions.

Map of Teravia, a fictional country, on a grid with columns A–F and rows 1–5; each grid square is 100 miles wide (scale bar: 90 pixels = 100 miles). The Western Ocean lies along the west edge (column A). Forest (over 40 inches of rain a year) covers row 1 and the top of row 2 in columns A–D. Grassland plains (20–40 inches of rain) cover the middle of the country. Desert (under 10 inches of rain) covers row 5. Mountains cover columns E and F in rows 1–4. The Amon River begins in the mountains in square F1/F2 and flows west through row 3 to the ocean. Cities: Port Sela (over 1,000,000 people) at the mouth of the river on the coast, square A3; Darro (250,000–1,000,000) on the river in square C3, exactly 200 miles east of Port Sela; Kesh (under 250,000) in the desert in square C5 next to a spring (underground water); Halven (under 250,000) in the mountains in square E4 next to a copper mine; Brinmoor (under 250,000) in the forest in square C1. Western Ocean Amon River A B C D E F 1 2 3 4 5 Port Sela Darro Kesh Halven Brinmoor N Legend Forest (over 40 in. of rain a year) Grassland plains (20–40 in. of rain) Desert (under 10 in. of rain) Mountains City over 1,000,000 people City of 250,000–1,000,000 Town under 250,000 Spring (underground water) Copper mine River 0 100 200 miles (each grid square is 100 miles wide) Teravia (a fictional country)

According to the map and legend, what is the most likely main economic activity in Halven?

Answer choices
Hint

Find Halven on the map, then match the symbol next to it with the legend.

Summary

  • People settle where there is water, flat fertile land, a moderate climate, and resources. Rivers and coasts attract the largest cities.
  • Agriculture began about 10,000 years ago in the Fertile Crescent and elsewhere. It created food surpluses, cities, and governments.
  • People depend on, adapt to, and modify the environment. Modifying it can backfire, as in the Dust Bowl and the shrinking Aral Sea.
  • Sustainability and conservation aim to protect resources. Renewable resources can be replaced. Nonrenewable ones cannot.
  • Read maps in order: title, legend, grid or latitude/longitude, scale. Use the scale to measure distance.
  • Percent change = (new − original) ÷ original × 100; population density = population ÷ area.
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